Example 10 - Example to evaluate the influence of transverse cracks in a rotating shaft.

In this example, we use the rotor seen in Example 10 for demonstrating the results obtained when we have a transversal crack present in the rotor system. In this case, the breathing behavior of the considered transversal crack is described according to the model proposed by Mayes and Davies (1984) and Gasch (1993).

import numpy as np
import scipy
import toml

import ross as rs
from ross.defects import *
from ross.defects.crack import crack_example
from ross.units import Q_

"""Create example rotor with given number of elements."""
steel2 = rs.Material(name="Steel", rho=7850, E=2.17e11, Poisson=0.2992610837438423)
#  Rotor with 6 DoFs, with internal damping, with 10 shaft elements, 2 disks and 2 bearings.
i_d = 0
o_d = 0.019
n = 33

# fmt: off
L = np.array(
        [0  ,  25,  64, 104, 124, 143, 175, 207, 239, 271,
         303, 335, 345, 355, 380, 408, 436, 466, 496, 526,
         556, 586, 614, 647, 657, 667, 702, 737, 772, 807,
         842, 862, 881, 914]
         )/ 1000
# fmt: on

L = [L[i] - L[i - 1] for i in range(1, len(L))]

shaft_elem = [
    rs.ShaftElement6DoF(
        material=steel2,
        L=l,
        idl=i_d,
        odl=o_d,
        idr=i_d,
        odr=o_d,
        alpha=8.0501,
        beta=1.0e-5,
        rotary_inertia=True,
        shear_effects=True,
    )
    for l in L
]

Id = 0.003844540885417
Ip = 0.007513248437500

disk0 = rs.DiskElement6DoF(n=12, m=2.6375, Id=Id, Ip=Ip)
disk1 = rs.DiskElement6DoF(n=24, m=2.6375, Id=Id, Ip=Ip)

kxx1 = 4.40e5
kyy1 = 4.6114e5
kzz = 0
cxx1 = 27.4
cyy1 = 2.505
czz = 0
kxx2 = 9.50e5
kyy2 = 1.09e8
cxx2 = 50.4
cyy2 = 100.4553

bearing0 = rs.BearingElement6DoF(
    n=4, kxx=kxx1, kyy=kyy1, cxx=cxx1, cyy=cyy1, kzz=kzz, czz=czz
)
bearing1 = rs.BearingElement6DoF(
    n=31, kxx=kxx2, kyy=kyy2, cxx=cxx2, cyy=cyy2, kzz=kzz, czz=czz
)

rotor = rs.Rotor(shaft_elem, [disk0, disk1], [bearing0, bearing1])

"""Inserting a mass and phase unbalance and defining the local response."""
massunbt = np.array([5e-4, 0])
phaseunbt = np.array([-np.pi / 2, 0])
probe1 = (14, 0)
probe2 = (22, 0)

crack = rotor.run_crack(
    dt=0.0001,
    tI=0,
    tF=5,
    depth_ratio=0.2,
    n_crack=18,
    speed=Q_(1200, "RPM"),
    unbalance_magnitude=massunbt,
    unbalance_phase=phaseunbt,
    crack_type="Gasch", #or crack_type="Mayes"
    print_progress=False,
)

"""Plots the time response for the two given probes."""
results = crack.run_time_response()
results.plot_1d([probe1, probe2]).show()

"""Plots the frequency response for the two given probes."""
crack.plot_dfft([probe1, probe2], range_freq=[0, 100], yaxis_type="log").show()